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Objective To evaluate the changes in the expression of cytochrome cholesterol side chain cleavage enzyme (P450scc) in the brain of morphine-dependent rats. Methods Twenty-four male SD rats aged 4-8 months weighing 180-200 g were randomly divided into 3 groups (n = 8 each): group Ⅰ normal saline (group NS), group Ⅱ morphine dependence (group MD) and group Ⅲ morphine withdrawal (group MW). In group MD and MW, the rats were given intraperitoneally increasing doses of morphine starting from 5 mg/kg to 10, 15, 20, 30, 40 and 50 mg/kg twice a day for 7 days. In group NS, the rats were given equal volume of normal saline instead of morphine. The rats were decapitated 1 h after last injection in group NS and MD. In group MW, naloxone 2 mg/kg was given 1 h after last injection, and then the animals were decapitated 30 min after withdrawal symptoms were observed. The brains were immediately removed and the frontal cortex, hippocampus, striatum and thalamus were separated. The expression of P450see was determined by Western blot. Results The expression of P450scc in the frontal cortex, hippocampus and striatum was significantly decreased in group MD and MW compared with group NS (P<0.05). Conclusion The down-regulation of P450scc expression might be involved in the development of morphine dependence, but it is not involved in the morphine withdrawal.
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Objective: To investigate the effects of the exogenous testosterone propionate on apoptosis of rat germ cells and the mechanisms thereof. Methods: Thirty 35-day-old male SD rats were randomly divided into experimental group and the control group. The rats in experimental group were injected (i.m.) testosterone propionate and the control group with an equal volume of saline. By using terminal deoxynueleotidy transferase nediated dUTP nick-end labeling (TUNEL), flow cytometry (FCM), radioimmunoassay (RIA) and electron microscopy, the quantity and quality of apoptosis of germ cells were evaluated. Results:(1) Compared with the control, the apoptotic number of rat germ cells was increased in the experimental group, especially the primary spermatocyte. The apoptotie rate was 11.3% detected by FCM in experimental group,while 3.6% in the control group (P ＜ 0.01). (2) The percentages of 1C were 21.8% in experimental group and 33.8% in control group (P ＜ 0.01).The percentages of 2C were 52.6% in experimental group and 37.1% in control group (P ＜ 0.01). (3) The serum levels of testosterone were (3 486.8±333.3) ng/L in experimental group and (846.9±167.5) ng/L in control group (P ＜ 0.01). The serum levels of follicle-stimulating hormone (FSH) were (2.5±0.8) IU/L in experimental group and (5.2±1.7) IU/L in control group (P ＜0.01). Conclusion: The exogenous testosterone propionate might induce apoptosis of germ cells by retroinhibition of the hypothalamie-pituitary-gonadal axis, thus having contraceptive effects.
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AIM To investigate if morphine addiction and relapse to morphine-seeking is related to the change in neurosteroid levels in the brain of rats. METHODS Rats were injected ip morphine (5 mg·kg-1·d-1, 18:00-20:00) and trained in conditioned place preference (CPP) box, once daily for 10 d. CPP test was performed 24 h after the last training. After discontinuation of training for 7 d for CPP extinction, then intermittent and inescapable foot-shock (FS, 0.5 mA, 0.5 s on, 40 s off, 15 min) was applied to rats as the priming stimuli for relapse. CPP test was performed 2 h after FS. When CPP test finished, rats were decapitated and the levels of neurosteroids were analyzed using gas chromatography/mass spectrometry. RESULTS CPP was established when rats were injected morphine and trained for 10 d. At the same time, the levels of pregnenolone and allopregnanolone in the brain tissues of rats were significantly increased. When CPP was reinstated in morphine-treated rats by FS-stress after 7 d CPP extinction, the levels of dehydroepiandrosterone and dehydroepiandrosterone sulfate were significantly increased. CONCLUSIONThe development of morphine addiction and relapse may be related to endogenous neurosteroids in rat brain tissues.
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Objective To investigate the expression of mRNAs for cholesterol side chain cleavage enzyme (p450 scc), 17?-hydroxylase / C17-20 lyase (P450 C17) and 3?-hydroxysteroid dehydrogenase (3?-HSD) in frontal cortex, amygdala, hippocampus, striatum and midbrain of morphine dependence rats.Methods Twenty-one male SD rats were randomly divided into 3 groups with 7 animals in each group: (1) control group (group C) ; (2) morphine dependence group (group D) and (3) morphine withdrawal group (group W). In group D and W the animals were given intraperitoneally increasing doses of morphine starting from 5 mg?kg-1 to 10, 15, 20, 30, 40 and 50 mg?kg-1 twice a day for 7 days. In group C the animals were given normal saline instead of morphine. In group C and D the animals were decapitated 1 h after last injection. In group W naloxone 2 mg?kg-1 was given 1h after last morphine injection, then the animals were decapitated 30 min after withdrawal symptoms were observed. The brains were immediately removed and the frontal cortex, amygdala, hippocampus, striatum and midbrain were separated. The expression of mRNAs for the three steroidogenic enzymes in the different brain regions of rats were determined by RT-PCR.Results The expression of P450scc mRNA in striatum and 3?-HSD mRNA in amygdala, striatum and frontal cortex decreased in group D compared with group C. The expression of 3?-HSD mRNA increased in morphine withdrawal group compared with group D.Conclusion The gene expression of steroidogenic enzymes decreases in some brain regions of morphine dependence rats, suggesting that endogenous neurosteroids might be involved in morphine dependence.